1、Designation: A756 17Standard Specification forStainless Anti-Friction Bearing Steel1This standard is issued under the fixed designation A756; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in pa
2、rentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This specification covers the requirements forchromium-carbon bearing quality stainless steel to be used inthe manufacture of anti-friction bearin
3、gs.1.2 Supplementary Requirements of an optional nature areprovided and when desired shall be so stated in the order.1.3 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information only
4、and are not considered standard.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade O
5、rganization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2A484/A484M Specification for General Requirements forStainless Steel Bars, Billets, and ForgingsA751 Test Methods, Practices, and Terminology for Chemi-cal Analysis of Steel ProductsE45 Test Methods for
6、 Determining the Inclusion Content ofSteelE381 Method of Macroetch Testing Steel Bars, Billets,Blooms, and ForgingsE1019 Test Methods for Determination of Carbon, Sulfur,Nitrogen, and Oxygen in Steel, Iron, Nickel, and CobaltAlloys by Various Combustion and Fusion TechniquesE1077 Test Methods for Es
7、timating the Depth of Decarbur-ization of Steel Specimens2.2 Other Standards:ISO 683 Part 17 Ball and Roller Bearing Steels3SAE J418a Grain Size Determination of Steel43. Ordering Information3.1 Orders for material under specification should includethe following information:3.1.1 Quantity,3.1.2 Grad
8、e identification,3.1.3 Specification designation and year of issue,3.1.4 Dimensions, shape, and3.1.5 Supplementary Requirements, if desired.4. Process4.1 The steel shall be made by a process that is capable ofproviding a high-quality product meeting the requirements ofthis specification.5. Chemical
9、Composition5.1 Typical examples of chemical compositions are shownin Table 1. Other compositions may be specified.5.2 An analysis of each heat of steel shall be made by thesteel manufacturer in accordance with Test Methods, Practices,and Terminology A751. The chemical composition thus deter-mined sh
10、all conform to the requirements specified in Table 1for the ordered grade or to requirements agreed upon betweenthe manufacturer and the purchaser.5.3 Product analysis may be made by the purchaser inaccordance with Test Methods, Practices, and TerminologyA751. Permissible variations in product analy
11、sis shall be madein accordance with Specification A484/A484M.6. Dimensions, Mass, and Permissible Variations6.1 The size and shape of the material shall be agreed uponbetween manufacturer and purchaser.6.2 Dimensional tolerances for hot-rolled or hot-rolled andannealed bars, in straight lengths or c
12、oils, and cold-finished1This specification is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloys and is the direct responsibility of SubcommitteeA01.28 on Bearing Steels.Current edition approved Sept. 1, 2017. Published October 2017. Originallyapproved in 1978.
13、Last previous edition approved in 2014 as A756 09(2014)1.DOI: 10.1520/A0756-17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page o
14、nthe ASTM website.3Available from International Organization for Standardization (ISO), ISOCentral Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier,Geneva, Switzerland, http:/www.iso.org.4Available from SAE International (SAE), 400 Commonwealth Dr., Warrendale,PA 15096, http:/www.s
15、ae.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardizati
16、on established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1bars 0.500 in. (12.7 mm) and larger in diameter furnished underthis specification shall conform t
17、o the requirements specified inthe latest edition of Specification A484/A484M.6.3 Dimensional tolerances for cold-finished coils for balland roller material shall be as shown in Table 2.6.4 Coil tolerances also apply to cold-finished straightlengths under 0.500 in. (12.7 mm) in diameter.7. Quality T
18、ests7.1 The supplier shall be held responsible for the quality ofthe material furnished and shall make the necessary tests toensure this quality. The supplier shall be required to report onthe results of the macroetch and microinclusion rating testsdetailed below. Quality tests shown in 7.2 through
19、7.4 arebased upon procedures established in Test Methods E45.7.2 SamplingSamples taken in accordance with the fol-lowing paragraphs shall be obtained from 4 by 4-in. (102 by102-mm) rolled billets or forged sections. Tests may be madeon smaller or larger sections by agreement with the purchaser.A min
20、imum 3 to 1 reduction of rolled billets or forged sectionsis required for strand cast products.7.2.1 For top poured products, a minimum of six samplesrepresenting the top and bottom of first, middle, and last usableingots shall be examined.7.2.2 For bottom poured products, a minimum of sixsamples sh
21、all be examined and they shall represent the top andbottom of three ingots. One ingot shall be taken at randomfrom the first usable plate poured, one ingot, at random, fromthe usable plate poured nearest to the middle of the heat, andone ingot, at random, from the last usable plate poured. Whentwo u
22、sable plates constitute a heat, two of the sample ingotsshall be selected from the second usable plate poured. Where asingle usable plate constitutes a heat, any three random ingotsmay be selected. Other methods of sampling shall be as agreedupon between the manufacturer and the purchaser.7.2.3 For
23、strand cast products, a minimum of six samplesrepresenting the first, middle, and last portion of the heat castshall be examined. At least one sample shall be taken fromeach strand.7.3 MacroetchSpecimens representative of the full crosssection of bars, billets, or blooms shall be macroetched andrate
24、d in accordance with Method E381 in hydrochloric acidand water (1:1) at a temperature of 160 to 180 F (71 to 82 C).Such specimens shall not exceed S2, R2, C2 of Method E381.Indications due to sulfur segregation (commonly referred to asType A segregates) are not to be included in the rating. Foringot
25、 cast material only, if the size and weight of the bars,billets, or blooms prevent the full cross section from beingmacroetched, an oversize quarter-section may be used as analternative. The quarter-section must meet the reduction re-quirement of 7.2 and contain both the surface and center of theori
26、ginal cross section before reduction.7.4 Inclusion RatingThe specimens shall be38 by34 in.(9.5 by 19.1 mm) and shall be taken from an area halfwaybetween the center and outside of the billet. The polished faceshall be longitudinal to the direction of rolling. The scale usedfor rating the specimens s
27、hall be the Jernkontoret chartdescribed in Test Methods E45, Plate I-A. Fields with sizes ornumbers of all types of inclusions intermediate betweenconfigurations shown on the chart shall be classified as thelesser of the rating number. The worst field of each inclusiontype from each specimen shall b
28、e recorded as the rating for thespecimen. Two thirds of all specimens and at least one fromeach ingot tested, or from the first, middle, and last portion ofthe strands tested, as well as the average of all specimens, shallnot exceed the rating specified in Table 3.8. Response to Heat Treatment8.1 Fo
29、r chemical composition 440C, specimens with sec-tions38 in. (9.5 mm) in thickness, cut from a bar, billet, orforging, shall be placed in a furnace that is at 1875 6 10 F(1023.8 6 5.5 C), allowed to heat to 1875 6 10 F, held atheat 25 min, and cooled in still air. Hardness of such specimensshall be n
30、ot lower than 58 HRC.8.2 Samples heat treated as in 8.1 shall show a fracture grainsize of No. 6 or finer. (See SAE J418a.)TABLE 1 Chemical CompositionA, BISOCName C MnP(max)S(max)Si Cr Ni MoCu(max)O(max)DAl (max) Other. 440C 0.951.20 1.00 max 0.040 0.030 1.00 max 16.0018.00 0.75 max 0.400.65 0.50 0
31、.0020 0.050 . X30CrMoN15-1 0.250.35 1.00 max 0.030 0.025 1.00 max 14.0016.00 0.300.50 0.851.10 . 0.0020 . N0.3000.500ISO X47Cr14 0.430.50 1.00 max 0.040 0.015 1.00 max 12.5014.50 . . . 0.0020 . .ISO X65Cr14 0.600.70 1.00 max 0.040 0.015 1.00 max 12.5014.50 . 0.75 max . 0.0020 . .ISO X108CrMo17 0.951
32、.20 1.00 max 0.040 0.015 1.00 max 16.0018.00 . 0.400.80 . 0.0020 . .ISO X40CrMoVN16-2 0.370.45 0.60 max 0.025 0.015 0.60 max 15.0016.50 0.30 max 1.501.90 . . . V0.200.40ISO X89CrMoV18-1 0.850.95 1.00 max 0.040 0.015 1.00 max 17.0019.00 . 0.901.30 . 0.0020 . V0.070.12AElements not quoted shall not be
33、 intentionally added to the steel without the agreement of the purchaser.BIntentional additions of calcium or calcium alloys for deoxidation or inclusion shape control are not permitted unless specifically approved by the purchaser.CSteels listed as ISO meet the requirements of ISO 683, Part 17, Thi
34、rd Edition, Table 3.DOxygen content applies to product analysis and shall be determined in accordance with Test Methods E1019.TABLE 2 Dimensional Tolerances for Cold-Finished CoilsSize, in. (mm) Total Tolerance, in. (mm)Through 0.096 (2.44) 0.002 (0.05)Over 0.096 to 0.270 (2.44 to 6.86), incl 0.003
35、(0.08)Over 0.270 to 0.750 (6.86 to 19.1), incl 0.004 (0.10)A756 1729. Decarburization and Surface Imperfections9.1 Decarburization and surface imperfections shall notexceed the limits specified in Table 4 and Table 5. Decarbur-ization shall be measured using the microscopical methodsdescribed in Tes
36、t Methods E1077.10. Microstructure and Hardness10.1 The material shall be free of excessive carbide segre-gation.10.2 When annealing is specified in the order, the steel shallhave a predominantly spheroidized microstructure and a hard-ness as specified in Table 6.10.3 Small sizes where Rockwell B sc
37、ale hardness readingsare impractical shall show a maximum tensile strength of115 000 psi (792 MPa).11. Inspection11.1 The manufacturer shall afford the purchasers inspectorall reasonable facilities necessary to satisfy him that thematerial is being produced and furnished in accordance withthis speci
38、fication. Mill inspection by the purchaser shall notinterfere unnecessarily with the manufacturers operations. Alltests and inspections shall be made at the place of manufacture,unless otherwise agreed to.12. Certification and Reports12.1 Upon request of the purchaser in the contract or order,a manu
39、facturers certification that the material was manufac-tured and tested in accordance with this specification, togetherwith a report of the test results, shall be furnished at the timeof the shipment.TABLE 3 Inclusion RatingRating UnitsType Thin Series Heavy SeriesA 2.0 1.5B 2.5 1.5C 2.0 1.5D 2.0 1.0
40、TABLE 4 Decarburization and Surface Imperfections for Coils and Bars for Balls and RollersSize, in. (mm)Decarburization or Surface Imperfections per Side, max, in. (mm)Hot-Rolled or Hot-Rolled AnnealedCold-FinishedAnnealedThrough 0.250 (6.35) 0.005 (0.13) 0.003 (0.08)Over 0.250 (6.35) to 0.500 (12.7
41、), incl 0.006 (0.15) 0.004 (0.10)Over 0.500 (12.7) to 0.750 (19.1), incl 0.008 (0.20) 0.006 (0.15)Over 0.750 (19.1) to 1.000 (25.4), incl 0.010 (0.25) 0.008 (0.20)TABLE 5 Decarburization and Surface Imperfections for Bars and TubesSize, in. (mm)Decarburization or Surface Imperfections per Side, max,
42、 in. (mm)Hot-Rolled BarsHot-Rolled Annealed Cold-Finished AnnealedBars Tubes Bars TubesThrough 1.000 (25.4) 0.012 (0.31) 0.015 (0.38) 0.012 (0.31) 0.012 (0.31) 0.010 (0.21)Over 1.000 (25.4) to 2.000 (50.8), incl 0.017 (0.43) 0.022 (0.56) 0.020 (0.51) 0.015 (0.38) 0.014 (0.36)Over 2.000 (50.8) to 3.0
43、00 (76.2), incl 0.025 (0.64) 0.030 (0.76) 0.030 (0.76) 0.025 (0.64) 0.019 (0.48)Over 3.000 (76.2) to 4.000 (101.6), incl 0.035 (0.89) 0.045 (1.14) 0.035 (0.89) 0.024 (0.61)Over 4.000 (101.6) to 5.000 (127.0), incl 0.055 (1.40) 0.065 (1.65) 0.040 (1.02) 0.028 (0.71)TABLE 6 Maximum Hardness for Anneal
44、ed MaterialMaximum HardnessProduct Condition Brinell RockwellCoils hot-rolled-annealed . . . 25 HRCBars and tubes hot-rolled-annealed 255 HB . . .Coils, bars, and tubes cold-drawn-annealed 255 HB 100 HRBCoils, bars, and tubes annealed-cold-drawn as agreed upon between the purchaser and the manufactu
45、rerA756 173SUPPLEMENTARY REQUIREMENTSOne or more of the Supplementary Requirements described below apply when included in thepurchasers order or contract. When so included, a Supplementary Requirement shall have the sameforce as if it were in the body of the specification. Supplementary Requirements
46、 details not fullydescribed shall be agreed upon between the purchaser and the supplier, but shall not negate any of therequirements in the body of the specification.S1. Residual ElementsS1.1 The purchaser may specify that the analysis oftitanium, aluminum, and/or oxygen (Test Methods E1019)beprovid
47、ed by agreement with the steel manufacturer. Thenumber and location of samples shall be by agreement betweenthe purchaser and manufacturer.S2. Calcium AdditionsS2.1 Intentional additions of calcium or calcium alloys fordeoxidation or inclusion shape control are not permitted unlessspecifically appro
48、ved by the purchaser. The use oflime orfluorspar, or both, in the steelmaking slag is acceptable.S3. Magnetic Particle MethodS3.1 The purchaser may specify that the magnetic particlemethod described be used in addition to the microinclusionrating system described in 7.4. The magnetic particle method
49、measures bearing steel cleanliness by evaluating the totallength of macroinclusions for a stated area or per unit area.Results are commonly expressed in millimetres per squaremetre.S3.2 SamplingSee 7.2.S3.3 Test specimens shall be straight cylinder quarter sec-tion samples prepared and examined in accordance with themagnetic particle method of Test Methods E45.S3.4 For purposes of calculation, an inclusion length shallbe taken as the mean length of the length bracket into which itfalls; that is, an inclusion in the116 to18-in. bracket
